Loki was a pretty terrible villain. He was far from the only problem with that movie, but yeah... pretty bad. I'm not happy about him being the villain in the Avengers movie, which otherwise looks like some good lighthearted action special effects fun stuff.
I suppose its a central problem of the premise, but another thing that bothered me about the movie was the timescales involved.
Loki and Thor have been princes for thousands of years. During that time I would expect they would have figured most of the stuff that was covered in the movie, and more importantly, their personalities would probably be hardly encoded enough that a year would be pretty minor to them, no matter what they went through.
Instead they act like 20 year olds, with malleable personalities, and not like people that have had hundreds of years to perfect everything they do and having personalities that are rigid with the weight of millenia.
And again, Loki. I honestly think that over thousands of years his companions and his brother would have noticed how slimy he is. The only other possibility is that he was completely honest and a nice guy for 2000 years, and then suddenly became evil, but that seems pretty crazy to me (although it does explain how terrible he is at lies).
Loki was a pretty terrible villain. He was far from the only problem with that movie, but yeah... pretty bad. I'm not happy about him being the villain in the Avengers movie, which otherwise looks like some good lighthearted action special effects fun stuff.
Hopefully he will be a better villain there, since he has 5 super heroes to outsmart and overpower for the first half of the movie (although at the end they will of course obligatorily crush him).